Pre-heat oven to 180C and line a baking tray with parchment paper or foil.
Crush saffron threads into a powder form in a pestle and mortar. Transfer saffron powder to a small teacup. Add 2 tbsps warm water, stir and set aside.
In a mixing bowl, beat butter and sugar until light and fluffy, about three minutes.
Add eggs one by one, till incorporated.
Add rose water and the reserved saffron water.
In batches, add rice flour, baking powder and sea salt. Mix gently, till incorporated into the mixture.
At this point, place the cookie dough in the mixing bowl straight into the fridge for 20-30 minutes for the dough to chill. Cover the bowl with foil, plastic wrap or a plate.
After the dough has rested in the fridge for the requisite amount of time, you will start to form the cookies.
Using a measuring tablespoon, scoop out 1 tablespoon of dough and place in the palm of your hand. Form into a ball and gently, press your thumb in the middle to form a well, flattening out the cookie at the same time.
Place each cookie on your baking tray and when they are all lined up on the tray, bake for 10 minutes.
Fill each "thumbprint" well of the cookie with your favourite jam or jelly and adorn with pistachio dust. Serve warm. If you want to take these to work, as I did - then add the jelly or jam into the well right before serving.
